Some of conventional spectroscopic apparatuses use a lamp or a ceramic heater as a light source, and disperse light emitted from the light source and then transmitted through a material or reflected from a material, by a diffraction grating or by means of interference. In addition, some of spectroscopic apparatuses for detecting presence of a material scan a subject surface while sweeping the wavelength of laser light, thereby visualizing a 2-dimensional distribution of the material (see PATENT LITERATURE, NON PATENT LITERATURE, etc.).